Method of making reconstituted marble



1968 w. D. GOODWIN ,37

METHOD OF MAKING RECONSTITUTED MARBLE Filed D80. 7, 1964 Stone pigwentB-STAGE Caialyat I Stone Vibrator B d t Shine 111 mg Agen Pigment M OvenRecotnshtutad Catalyst ASTAGE 5 one INVENTGR.

William D. Goodwih BY J YW AT TORNE YS United States Patent Office3,371,135 METHOD MAKING RECGNSTETUIED h iARELE William D. Goodwin, 445Bishop St. NW., Atlanta, Ga. 30313 Filed Dec. 7, 1964, et. No. 416,43ll6 Claims. (Cl. N h-63) ABSTRAQT 0F THE DESCLUSURE A method of making anarticle or body of reconstituted marble, wherein sotnes of selected sizeare combined with a resin matrix, vibrating the mixture to stratify thestones, curing the resin, heating the material, and cooling.

Cross reference to related applications The present invention is animprovement over the invention disclosed in the co-pending applicationof William D. Goodwin, Serial No. 377,631, filed June 24, 1964, forReconstituted Marble and Method of Making Same, and includes many of thefeatures and advantages disclosed therein.

Background of the invention Though previous methods of makingreconstituted marble and other reconstituted stones have provided aproduct that has many uses and is quite acceptable for many purposes, ithas been found that certain qualities are somewhat less than aredesired. Some of the primary problems with reconstituted marble havebeen solved in the method disclosed in the above identified co-pendingapplication; however, there is still the problem that the properties ofreconstituted stones are due in large part to the binding agent that isused to put together the small particles of stone or other granularmaterial.

At present, some of the more desirable binding agents available are thevarious synthetic resins. Resins have the desirable qualities ofresistance to a relatively high degree of temperature, resistance tovarious acids, alkalis and other chemicals, and ease of handling to makethe re constituted stone. However, the wearing quality and heatresisting qualities hardly rival the properties of genuine stone; also,the granular stone, when adhered with a resin, provides a surface sheenor glossiness without providing the visual sensation of'depth of thematerial. In natural stone, light passes into the stone and is reflectedfrom the innerfaces of crystals as well as from the surface of thestone, thus providing a sensation of depth along with a surfaceglossiness.

Previous reconstituted stones have not caused a visual sensation ofdepth because they have been made up of very fine particulate stone heldtogether by some binding agent; and, the small particles reflectsubstantially all of the light that strikes the surface, either at thesurface of the material or at a very short distance below the surface,any distance below the surface being very slight. Further, sincesubstantially all of the light is reflected, the material has a whiteappearance regardless of the color of stone comprising the material.

Summary of the invention The present invention overcomes the abovementioned objections by providing a method of preparing a material whichincludes relatively large particles of stone at the surface, with onlythe interstices filled with the very small particles of stone. With thisstructure, it will be seen that light can penetrate into the particlesof stone and be reflected from within the particles of stone so that aperson is literally looking into the material. Further, the light thatpenetrates into the material will be partially absorbed (more so thanthat which is reflected from the outer surface) to make the interior ofthe material appear somewhat darker; and, it is well known that, whenthe eye perceives a darker area, the darker area is interpreted as beingfarther away than the lighter areas; hence, the material will provide avisual sensation of depth.

Since the surface fabricated by the material of the present inventionhas relatively large particles of stone, the interstices between thelarge particles can be filled with very small particles to provide asurface that is predominately stone rather than binding agent, whichwill give to the reconstituted stone many qualities of stone rather thanqualities of the binding agent.

These and other features and advantages of the present invention willbecome apparent from consideration of the following specification whentaken in conjunction with the accompanying drawing.

Brief description of the drawing FIG. 1 is a schematic presentation of aprocess to make reconstituted stone according to the present invention;and,

FIG. 2 is a schematic presentation of an alternate process.

Description of the embodiments It will be understood that many basictechniques can be used in conjunction with the present invention toprovide a reconstituted stone; however, it is preferable to use aprocess such as the one disclosed in the above identified co-pendingapplication.

Referring to FIG. 1, it will be seen that the stone and binding agent,as well as a catalyst, and perhaps a pigmenting material, are mixedtogether, and the binding agent is allowed to reach its B-stage ofcuring. The entire mass of material is then placed into a mixer, and apigment is added to produce the desired streaks or the like; then, thematerial is placed into a mold.

It will be understood that the process thus far is the same as thatdisclosed in the above mentioned co-pending application; however, theoriginal mixture is somewhat different because stone including largerparticles is used, whereas stone having a very small particle size isnormally used for such processes. The reconstituted stone of the presentinvention includes particles that will just pass through a number 6screen, in U.S. screens, although it also includes smaller particleswhich would be retained on a number 200 screen. This will be discussedin more detail hereinafter.

This crushed stone including the larger particles of the stone is mixedwith the binding agent, catalyst, and perhaps pigment, and placed into amold. While the mass is in the mold, the while the binding agent isstill in the B-stage, the mold is vibrated. The purpose of the vibrationis to cause the larger particles of stone to move toward the bottom ofthe mold. The length of time that the mold is vibrated can be variedwidely depending partially on the density desired in the bottom surfaceof the material; however, it has been found that the mold needs to bevibrated at least twenty (20) seconds in order to give any noticeableresult; and, vibration for a time of sixty to ninety seconds has beenfound to give desirable results. It will of course be understood thatthe mold can be vibrated throughout the time that the material is in themold if desired.

During the vibrating of the mold, the larger particles of the stone movetoward the bottom of the mold displacing the smaller particles, so thatthe bottom surface of the material in the mold becomes quite dense dueto the preponderance of larger particles with their interstices filledwith the smaller particles. It will of course be understood that thesurface of the material that is against the bottom of the mold is thesurface to be used, i.e., the finished side of the material.

In order to provide the high density of the material, and have somerelatively large particles of stone, three basic sizes of particles areused. The largest size particle is such that one percent (1%) of thestone will be retained on a number 6 screen, and fifteen percent of thestone will be retained on a number 14 screen; the medium size particlesare of such size that substantially all of the stone will pass through anumber 16 screen and substantially all of the stone will be retained ona number 60 screen; and, the smallest particles are of such size thatsubstantially all of the stone will pass through a number 4-0 screen andsubstantially all the stone will be retained on a number 200 screen.These three sizes of particles of stone have been mixed to providetwenty-five percent of the largest particles, twenty-five percent (25%)of the medium size particles, and forty percent of the smallestparticles, the remaining ten percent (10%) being the binding agent andpigments; and, all percentages are percentages of the total weight. Thismixture gives a very good quality of reconstituted marble, but the exactpercentages are not intended to be slavishly followed. The percentagescan be varied by plus or minus three percent (i3%) without appreciablyaffecting the quality of the finished product.

With the above mixture, it will be now seen that, when the stone ismixed with the resin or other binding agent, placed into a mold, and themold vibrated, the largest particles will move toward the bottom of themold; however, the bottom surface of the mass will not be composedentirely of the largest particles; rather, the largest particles willsimply displace enough of the smaller particles for them to take theirown position. This will yield a surface having a high percentage of thelargest particles with the medium size and smallest particles being usedto fill the interstices between the largest particles.

While one of the primary purposes of the arrangement of particles is toprovide relatively large particles at the surface of the finishedmaterial in order to give the material the characteristics of stone,another advantage of the internal structure of the material is that thelargest particles are sufficiently large to be well set into thematerial so that they are less likely to come out when subjected toabrasion or vibration; further, the smaller particles will completelysurround the largest particles to give greater mechanical support forthe largest particles. It will thus be seen that the entire structure isvery well bonded together to provide a very durable material.

An alternative method of making reconstituted stone is shown in FIG. 2of the drawings. The principal difference in the procedure of the methodshown in FIG. 2 is the placing of the resin into the mold while theresin is in its A-stage, and adding the stone to the resin in the mold.

In more detail, the resin or other binding agent is mixed with a pigmentand, while the resin is in its A-stage, placed into a mold. The crushedstone is poured into the resin and spread evenly throughout the mold.Though it may be desirable to vibrate the mold to move the largeparticles toward the bottom of the mold as described above, it iscontemplated that sufiicient large particles will be used to make ahomogeneous material, the large particles being uniformly distributed inthe material.

The principal advantages of this alternate method are that there is noone finished surface; rather, any surface can be polished, and even acut edge can be polished to have an attractive appearance. Also, withthis method, there is less danger of having air bubbles. Since the resinis in its A-stage, and has a very low viscosity at the time the stone isadded, any air bubbles will readily rise to the surface and the air willescape.

It will thus be seen that this method of making reconstituted stone isvery simple and will provide a stone of homogeneous characteristics.

It will be realized that naturally formed marble sometimes has pieces ofmica therein which give an extra shininess to the marble, and sometimesprovide a spot of almost mirror-like brilliance. This feature can beduplicated in the present reconstituted marble by adding about three tofive percent (3 to 5%) by volume of mica to the material, for example,to the crushed stone. This percentage can of course be varied widelydepending upon the appearance desired.

When the binding agent is completely cured, or cured to the extent thatthe material has sufficient rigidity to support its own weight, thematerial is removed from the mold and placed into an oven or the like tobe heated. The purpose of the heating is to drive off a substantialportion of the binding agent that is on the surface of the material, andthis is discussed in more detail in the above identified co-pendingapplication. After the binding agent has been driven off, the materialcan be removed from the oven and polished to be ready for use. It willbe understood that the side of the material that was at the bottom ofthe mold is the finished side of the material, and is the only side thatrequires polishing; but, in the second embodiment discussed, all sidesmay be regarded as finished sides, and may be polished.

It will be now seen that the present invention provides a reconstitutedstone that is very similar to naturally formed stone, both as to visualcharacteristics and physical characteristics. The large percentage ofstone in the finished surface of the material provides a denseness,resistance to heat, and resistance to wear or abrasion rivalingnaturally formed marble; and, the larger particles provide a visualsensation of depth as discussed above. The material can be made quiteinexpensively, and the characteristics can be changed somewhat to suitany particular application.

It will be understood by those skilled in the art that the particularembodiment of the invention herein presented is by way of illustrationonly, and is meant to be in no way restrictive; therefore, numerouschanges and modifications may 'be made, and the full use of equivalentsresorted to, without departing from the spirit or scope of the inventionas defined by the appended claims.

What is claimed as invention is:

1. A process of making a reconstituted stone including the steps of:

( 1) preparing a mixture comprising:

(a) stone, constituting approximately 25 percent large stone particlesof 6 to 14 screen size, approximately 25 percent medium stone particlesof 16-60 screen size, approximately 40 percent small stone particles of40-200 screen size;

(b) a binding agent, and

(c) a catalyst;

(2) placing the mixture in a mixer and mixing the mixture;

(3) placing the mixture in a mold and vibrating the mold to cause thelarger particles of stone to migrate toward the bottom of the mold;

(4) curing the binding agent to render the mixture a self sustainingmaterial;

(5) removing the self sustaining material from the mold:

(6) placing the self sustaining material in an oven and heating thematerial to drive off the binding agent from the surface of thematerial; and

(7) removing the material from the oven, and cooling the material.

2. The invention of claim 1 wherein the step of remov ing the materialfrom the oven and cooling the material is followed by the step ofpolishing the exterior surface of the material to the desired finish.

5 6 3. The invention of claim 1 wherein the step of prematerial to driveofi" the binding agent from the sur paring a mixture includes adding apigment to the mixface of the material; and ture. (6) removing thematerial from the oven and cooling 4. The invention of claim 1 whereinthe step of placthe material. ing the mixture in a mixer and mixing themixture in- 5 6. The invention of claim 5 wherein the step of addeludesaddin a pigment to th mi t e, ing stone to the mixture comprises addingmarble stone 5. A process of making a reconstituted stone including tothe mixture, and further includes adding 3 t Patent th steps f; mica tothe mixture.

(1) Preparing a mixture comprising:

(a) a binding agent; References Cited ('b) a catalyst, and UNITED STATESPATENTS c e 2,951,001 8/1960 Rubenstein 161-91 X (2) placing the mixturein a mold and adding stone 23 4 1/1966 Iva-Son et a1 X constitutingapproximately percent large stone 1,841,215 1/1932 Schneider 264 44particles of 6 to 14 screen size, approximately 25 1 3,247,294 3/1966Sabouni 264 44 percent medium stone particles of 16-60 screen size,2,517,100 8/1950 Erdle X approximately percent small stone particles of3,012,287 12/1961 Tucker 264 139 40-200 screen size, and dispersing thestone through- (3) curing the binding agent to render the mixture a 20147,506 10/ 1962 Poland.

self sustaining material;

(4) removing the material from the mold; ROBERT WHITE Primary Examiner(5) placing the material in an oven and heating the R. B. MOFFITT,Assistant Examiner.

